Printing inks and vehicles therefor



atented Dec. 4, 1945 I I PNITED STATES PATENT OFFICE I v 2,390,123 rrnm'rmo mxs AND vnmcLas 'rnannron Charles A. Riets, Park Ridge, andFrancis J.

Jeuck, Chicago, 11L, minors to Inter-chemical gcfiporation, New York, N.Y., a corporation cl No Drawing. Application July 22, 1942,

. Serial No. 451,954

' 11 Claims. 106-30) This invention relates to printing ink which or acompletely insoluble film-forming agent are dry by evaporation ofsolvent in the vehicle. distributed in colloidal form throughout the ve-More particularly, the invention contemplates the hicle. However,film-forming agents which are provisi n of an improved printing inkvehicle partiallvsoluble' in the ink vehicle are most often which 1 setmore effectively when heat is ap- 5 usedfin such event, the total amountpresent in plied to the printed film and which permits even the vehiclewill be such as to produce saturation greater speeds oi printing andgreater economy of the vehicle, plus an additional insoluble perin theprinting process. centage in the indicated range, distributed in col-Ordinary linseed oil inks dry by oxidation 01. loidal form throughoutthe vehicle. the ink vehicle and consequently cannot be print. It isimportant to have the film-forming agent ed at the high speeds demandedtoday even when distributed in colloidal rorm through the vehicle.

various drlers are included in the ink. At pres- It the agent is not incolloidal form, or if more.

ent, such inks are primarily used in sheet-fed than about 6% of it ispresent in the vehicle in presses, and it is necessary to use slipsheets 0011011181 0 .'l 00 Printing results, p rticularly and/oronset-preventing powders to prevent the in half-tone work.

transfer of the freshly printed ink from one sheet The addedfilm-forming agent, being insoluble to the next; and in some cases heatis used to in the solvent and vehicle, has little efiect on theaccelerate the drying. body of the ink at printing temperatures and con-The problem of high speed printing on other centrations. However, as theconcentration oi! than porous stock was solved with the introducresin(which is apparently a solvent for the filmtion of the inks disclosed inA. E. Gessler Patforming agent) goes up, on evaporation of solent No.2,087,190, dated July 13, 1937, These vent, the film-forming agent goesincreasingly ininks consist of pigment dispersed inavehicle comtosolution; the solution of resin, solvent and prising binder dissolved ina solvent which is not film-forming agent is far stifier than the resin.volatile at normal room temperatures (about 70 solvent mixture alone,and thus we obtain en- F.) ,but which evaporates rapidly when heated tohanced drying.

elevated temperatures (about 240 F.). Inks of Even better results areobtained, in heat-drythis character are quickly and eifectively dried bying, where suflicient insoluble film-forming agent passing them throughan oven which may be heatis present so that it does not go completelyinto ed by means of open flames so that the solvent solutionon-evaporation oi the solvent. Apparvapors will be burned. However, dueto the ently the colloidally'distributed insoluble material amount ofheat required to dry the solvent inks substantially reduces thestickiness oi the film, that are now available, the cost of heating isan Probably acting as an ofi'set Preventing medium, importantconsideration in the ultimate cost of and perhaps as an adsorbent. Thiseffect is subthe printing process; Furthermore, there are 85 stantialenough so that enhanced heat-drying many kinds of paper upon which theintense can be obtained even when completely insoluble heat required foreflective drying has an undefllm forming agents are used, as describedin our sirable efiect. In addition, attempts are constantco-pendingapplication Serial No. 451,764, filed ly being made to increase thespeed and decrease July 2 194 the cost or the printing process. a 40 Toobtain the desired colloidal distribution of We have discovered a newand improved printthe small percentage of film-forming agent, more ingink 01' the binder-solvent type which perthan mere stirring, mixing, orgrinding of the mits increased speeds in the printing process at agentin powder form into the vehicle is desirable. less cost than is possiblewith ink heretofore We have found that the colloidal distribution canavailable. This new ink comprises pigment disbe obtained by heating thevehicle, with the filmpersed in a vehicle consisting of resin dissolvedforming agent added thereto, to a temperature in a solvent which issubstantially non-volatile at above the melting point ofthe film-formingagent ordinary room temperatures (about 7 F), but and maintaining themixture at that temperature which evaporates rapidly when heated toelefor a period suificient to melt the film-forming vated temperatures(about 240 F), said vehicle agent. Then upon cooling of the vehicle toroom having a small percentage (about /2 to 6%) oi "temperature thefilm-forming agent separates out a film-forming agent colloidallydistributed or the mixture to form the desired colloidal through thevehicle. The film-forming agent is pension. It is also possible toobtain the proper characterized by the fact that it is at leastlargecolloidal distribution by dissolving the film-formly insoluble inthe ink vehicle at ordinary teming agent in a solvent, adding thesolution to the peratures, and at elevated temperatures well beinkvehicle to obtain a uniform mixture, and th n low its fusion point, butbecomes more soluble in evaporating the solvent, preferably whilegrindthe vehicle as the solvent is lost. ing the ink, so that thefilm-forming agent se The improved results are obtained when smallarates out of the ink in colloidal form. A third percentages (from 0.5to 6% of the ink vehicle) 0 method comprises malaxation of the insolubleLime These are melted together in an open kettle at a temperature of 350F., and after melting add slowly, allowing time for reaction betweenadditions When reaction is completed and foam is dow ,add

Ethyl cellulose (20 centipoise, high ethoxy content Close kettle andheat to 410 F., holding 4 at that temperature for two hours. Aftercooling, add- Solvent (petroleum out, having a distillation range of 5%at 497 F. and 95% at 527 F., having a dimethyl sulfate value of 3.0) 900In this limed rosin varnish, the film-forming agent is ethyl celluloseand constitutes about 3.2% of the total varnish, some of which goes intosolution, but the majority of which is distributed in colloidal formthroughout the varnish. This varnish has a mushy consistency due to thecolloidal distribution of ethyl cellulose. However, one pass on athree-roller mill renders it freeflowing.

Inks made from this vehicle print well, and can be dried much morerapidly than similar inks without the ethyl cellulose added. The amountof ethyl cellulose used is sufilcient to more than saturate the vehicleat dryness-hence, the added drying eflect of the distributed ethylcellulose can be observed here.

Example 2 Parts by weight Solvent (petroleum cut, having a distillationrange of 5% at 475 F. and 95% at 500 F.,

When reaction is complete, add- Ethyl cellulose (20 centipoise, highethoxy content) Heat to 410 F. and hold at that temperature for only 30minutes. When cooled,

Solvent (petroleum cut, having a distillation range of 5% at 475 F. and95% at 500 F., and a dimethyl sulfate value of 2.5)

In this example, the ethyl cellulose only constitutes about 1.2% of thetotal varnish. Most of this is insoluble in the vehicle under printingconditions, but becomes soluble under drying conditions.

Example 3 Pounds Terpene-phenol resin (Durez 220) 450 Solvent (petroleumdistillate-distillation range of 5% at 513 F. and at 542 F., dimethylsulfate value of 3.0)

are refluxed at 410-420 F. until the resin is dissolved.

Ethyl cellulose (20 centip0ise=medium ethoxy content) are then added,and the mass held at 410- 420 F. for 30 minutes Solvent are then added.

This vehicle shows a most pronounced change in solubility as solvent islost and resin solids increase. However, a small percentage of insolubleethyl cellulose generally remains to add to the effect of that whichgoes into solution.

An example of an ink made with one of the vehicles described above is asfollows:

Example 4 Parts by weight Varnish of Example 3, or 01' the other ex-This produced a black ink which dried rapidly and without offset at webspeeds of about 1200- 1400 feet per minute.

Obviously, other pigments, fillers and ingredients conventionally usedin inks (waxes, soaps, wetting agents, etc.) can be used to replacethose indicated.

While the examples are restricted to various grades of ethyl cellulose,other film-forming agents which exhibit the desired solubilities can beused. Thus, we have used nitrocellulose with alkyd resins which have asolvent action thereon; and other cellulose esters and, ethers, andvarious resins, can all be used.

While the invention is particularly applicable to heat-drying inks, itis obviously applicable in hastening the drying of any resin-solventfilmforming composition, whether air-dried or heatdried.

We claim:

1. A typographic printing ink vehicle comprising a solution of a resinin a solvent therefor, which is substantially non-volatile at 70 F., butwhich evaporates rapidly when heated to temperatures of the order of 240F., having a small percentage of a film-forming 'agent distributed incolloidal form therethrough, said small persubstantially volatile at 70F., but rapidly volatile at temperatures of the orderof 240 F., having asmall percentage of a film-forming agent distributed in colloidal iormtherethrough, said small percentage of film-forming agent comprisingfrom 0.5 to 6%, based on total vehicle weight,

of material insoluble in the solvent and the resin solution at normalroom temperatures, but becoming increasingly soluble as the resinconcentration of the solution increases by removal of solvent, wherebythe film obtained from the ink is further advanced in dryness bysolution of the film-forming agent.

3. A printing ink vehicle comprising a solution of a resin in ahydrocarbon liquid substantially non-volatile at 70 F., but whichevaporates rapidly when heated to temperatures of the order of 240 F.,having a small percentage of a filmiorming agent distributed incolloidal form therethrough, a portion of said film-forming agent beingsoluble in the resin solution, but a portion thereof, from 0.5 to 6%,based on total vehicle weight, be ng insoluble in the solvent and theresin solution at normal room temperatures, but becoming increasinglysoluble as the resin concentration of the solution increases by removalof solvent, whereby the film obtained from the ink is further advancedin dryness by solution of the film-forming agent.

4. A typograph c printing ink vehicle comprising limed rosin dissolvedin a low solvency petroleum hydrocarbon substantially non-volatile at 70F., but rapidly volatile at temperatures of the order of 240- F., thevehicle having from 0.5 to 6% of ethyl cellulose dispersed through thevehicle in colloidal form, a substantial portion of said ethyl cellulosebeing insoluble in the solvent and the resin solution at normal roomtemperatures, but becoming increasingly soluble as the resinconcentration of the solution increases by removaloi solvent,whereby'the film obtained from the ink is further advanced in dryness bysolution of the film-forming agent.

5. A typographic printing ink vehicle comprising terpene phenol resindissolved in a low solvency petroleum hydrocarbon substantiallynonvolatile at 70 F.. but rapidly volatile at temperatures of the orderof 240 F., the vehicle having from 0.5 to 6% tial portion of said ethylcellulose being insoluble in the solvent and the resin solution atnormal room temperatures, but becoming increasingly soluble as the resinconcentration of the solution increases by removal of solvent, wherebythe film obtained from the ink is further advanced in dryness bysolution of the film-forming agent.

of ethyl cellulose dispersedthrough the vehicle in colloidal form, asubstan- 6. A printing ink vehicle comprising a solution of a resin in asolvent therefor which is substantially non-volatile at F. but rapidlyvolatile at temperatures of the order of 240 F., together with anotherfilm-forming agent, the filmforming agent being slightly soluble in theresin solution, being present in quantity from 0.5 to 6%, based oi'itotal vehicle weight, above that required to saturate the resinsolution, said excess being distributed in colloidal form in thesolution, the film-forming agent being characterized by its increasedsolubility in the resin solvent combination as the percentage of resinincreases.

7. A printing ink vehicle comprising a solution of a resin in a solventtherefor which is substantially non-volatile at 70 F. but rapidlyvolatile at temperatures of the order of 240 F., together with anotherfilm-forming agent, the film-forming agent being slightly soluble in theresin solution, being present in quantity from 0.5 to 6%,

based on total vehicle weight, above that required to saturate the resinsolution, said excess being distributed in colloidal form in thesolution, the film-forming agent being characterized by its increasedsolubility in the resin solvent combination as the percentage of resinincreases, but not of such greatly increased solubilit that it iscompletely dissolved in the resin solution when a filmthereof is set tothe touch.

8. A printing ink comprising pigment dispersed in the vehicle of claim2.

9. A printing ink comprising in the vehicle of claim 6.

10. A heat-drying ink comprising pigment dispersed in a vehicle comprisng essentially a solution of limed rosin in a petroleum hydrocarbonliquid which is a non-solvent for high ethoxy ethyl cellulose and issubstantially non-volatile at 70 F., but rapidly volatile at 240 F.,having colloidally dispersed therein from 0.5 to 6% of high ethoxy ethylcellulose, the proportion of limed rosin to hydrocarbon being such thatthe ethyl cellulose is insoluble in the resin solution at normal roomtemperatures, but becoming increasingly soluble as the resinconcentration of the solution increases by removal of solvent, wherebythe film obtained from the ink is further advanced in dryness bysolution of the ethyl cellulose.

11. A heat-drying printing ink comprising pig... ment dispersed inavehicle comprising essentially a solution of a terpene phenolic resin ina petroleum hydrocarbon liquid which is a non-solvent for ethylcellulose and is substantiall nonvolatile at 70 F'., but rapidlyvolatile at 240 F., having collodally dispersed therein from 0.5 to 6%of ethyl cellulose, the proportion of terpene phenolic resin tohydrocarbon being such that the ethyl cellulose is insoluble in theresin solution at normal room temperatures, but becoming increasinglysoluble as the resin concentration of the solution increases by removalof solvent, whereby the film obtained from the ink'ls further advancedin dryness by solution of the ethyl cellulose.

pigment dispersed CHARLES A. RIETZ. FRANCIS J. .JEUCK.

